Neutron imaging of Zr–1%Nb fuel cladding material containing hydrogen

Hydrogen distribution and hydride phases were analyzed in reactor fuel cladding pressure tube Zr–1%Nb material up to 13,300 ppm. From neutron diffraction measurements, formation of cubic δ-ZrH2 and a small amount of tetragonal γ-ZrH was established. Texture effects were analyzed by imaging plate technique. From neutron radiography images a linear model was set up that adequately described the relationship between gray levels and nominal H-concentrations. The H-distribution was unveiled by 3D intensity histograms and fractal analysis of multilevel-segmented neutron radiography images.